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Biomedical subjects

W M Tang

Publications and source records attributed to W M Tang.

At least 37 records · Page 2Linked to original sources
PubMed2003

Group G streptococcus--a rare cause of osteomyelitis simulating bone tumour: a case report.

We report a case of osteomyelitis of the proximal femur caused by Lancefield group G streptococcus in a 71-year-old otherwise healthy man. The organism has rarely been identified as the cause of osteomyelitis. The subacute nature of the symptoms and the radiological appearance of the femur in this patient mimic bone tumour. The patient was successfully treated with conservative methods, including a prolonged period of oral antibiotics. We stress the importance of histological and bacteriological evidence in avoiding misdiagnosing patients with equivocal clinical and radiological presentation.

Aged↗
PubMed2002

Size scaling of turbulent transport in magnetically confined plasmas.

Transport scaling with respect to device size in magnetically confined plasmas is critically examined for electrostatic ion-temperature-gradient turbulence using global gyrokinetic particle simulations. It is found, by varying device size normalized by ion gyroradius while keeping other dimensionless plasma parameters fixed, that fluctuation scale length is microscopic in the presence of zonal flows. The local transport coefficient exhibits a gradual transition from a Bohm-like scaling for device sizes corresponding to present-day experiments to a gyro-Bohm scaling for future larger devices.

Journal Article↗
PubMed2002

Review article: knee flexion after total knee arthroplasty.

Many factors affect or predict the flexion range achieved after total knee arthroplasty. While the knees that have good preoperative flexion have better final flexion, knees with good preoperative flexion do lose some flexion whereas those with poor preoperative flexion can gain flexion. Although studies of different prosthetic designs have produced conflicting results, recent studies appear to favour posterior cruciate ligament (PCL)--substituting over PCL-retaining prostheses. Several factors related to surgical techniques have been found to be important. These include the tightness of the retained posterior cruciate ligament, the elevation of the joint line, increased patellar thickness, and a trapezoidal flexion gap. Vigorous rehabilitation after surgery appears useful, while continuous passive motion has not been found to be effective. Obesity and previous surgery are poor prognostic factors; certain cultural factors, such as the Japanese style of sitting, offer 'unintentional' passive flexion and result in patients with better range. If the flexion after surgery is unsatisfactory, manipulation under anaesthesia within 3 months of the total knee arthroplasty can be beneficial.

Arthroplasty, Replacement, Knee↗
PubMed2001

Primary total hip arthroplasty in patients with rheumatoid arthritis.

Twenty-eight (11 cemented and 17 noncemented) total hip arthroplasties (THA) were performed in 20 patients with rheumatoid arthritis (RA). The average age at operation was 42.1 years and the average follow-up was 10.8 years. There were two deep infections requiring removal of the prosthesis. Three cemented acetabular cups and one cemented femoral component were revised due to aseptic loosening. One cemented cup was loosened radiologically. One PCA polyethylene liner was revised because of significant wear. Both cemented and noncemented femoral components are capable of providing respectable results in RA patients. The relatively inferior results of THA among RA patients is due not only to the fixation method, but also to the poorer bone quality.

Activities of Daily Living↗
PubMed2001

Charnley total hip arthroplasty in Chinese patients less than 40 years old.

Forty-seven total hip arthroplasties were reviewed in 33 Chinese patients who were <40 years old at the time of operation. The preoperative diagnosis was avascular necrosis in 40% of the hips. A Charnley prosthesis was inserted using early cementing techniques in every hip. The average follow-up was 14.9 years (range, 6.9-21.1 years). The mean preoperative Harris hip score was 43.8 (range, 26-74), and the mean score at latest follow-up was 87.7 (range, 74-99) for the surviving hips. Thirty hips (63%) were revised, and 1 hip was removed because of late deep infection. The main cause of failure was aseptic loosening of the acetabular component. Using revision and radiologic loosening as endpoints, the cumulative survival rate for the acetabular component was 86.3% at 10 years and 27.0% at 15 years. The survival of the femoral components was 81.3% at 15 years. Patients with avascular necrosis had a higher failure rate than patients with other diagnoses (P =.001). An area of cement mantle that was <2 mm thick affected adversely the survival rate of the acetabular components (P =.04).

Adolescent↗
PubMed2001

Cementless total hip arthroplasty in young Chinese patients: a comparison of 2 different prostheses.

Sixty-one primary cementless total hip arthroplasties were performed in 45 Chinese patients <40 years old. There were 27 Anatomic Medullary Locking (AML, Depuy, Warsaw, IN) prostheses and 34 Porous Coated Anatomic (PCA, Howmedica, Rutherford, NJ) prostheses. The average follow-up was 7.6 years (range, 3-11 years). Ten hips (16%) were reoperated; the reason was polyethylene wear with or without osteolysis in 7 hips. Osteolytic lesion was present in 34 hips (56%). The cumulative successful rate at 10 years was 67% using reoperation for any reason as the endpoint. The cumulative successful rate was 98%, however, if revision for aseptic loosening was used as the endpoint. The 2 prostheses did not show significant differences in most parameters except that the PCA hips had significantly more acetabular loosening (P =.02) and periprosthetic osteolysis (P =.01).

Adult↗
PubMed2001

Bilateral total knee arthroplasty: One mobile-bearing and one fixed-bearing.

We compared the early results of mobile-bearing knee prosthesis with fixed-bearing knee prosthesis in 16 patients who had one-stage, sequential, bilateral replacements. In each patient, a Low Contact Stress (LCS, Depuy) rotating-platform prosthesis was inserted in one side, and an Anatomic Modular Knee (AMK, Depuy) posterior-stabilised prosthesis was inserted in the other side. The same surgical routines were adopted for both sides in each patient. There were significant improvements in the Knee Society knee score and functional score, as well as the Oxford Knee score after both mobile-bearing and fixed-bearing knee replacements (p<0.001). However, we could not find any significant difference between the clinical results of the two prostheses. The authors early experience with the mobile-bearing total knee prosthesis was as favourable as the medium-term experience of the fixed-bearing total knee prosthesis in this prospective, match-pair study.

Journal Article↗
PubMed2001

Review Article: Polyethylene wear and osteolysis in total hip arthroplasty.

Polyethylene wear has been accepted as a major cause of osteolysis in total hip arthroplasty. Submicron particles, which are secondary to abrasive wear, migrate into the effective joint space and stimulate a foreign-body response resulting in bone loss which is mainly mediated by macrophages. Diagnosis depends on serial radiographic evaluation and frequent follow-up. Polyethylene wear and osteolysis can be prevented by reducing the wear such as using a small femoral head, adaptive polyethylene thickness, suitable surgical techniques, non-polyethylene articulation, etc. The presence of cement or circumferential coatings may also retard the distal migration of particles. Medicines such as NSAIDs and bisphosphonate appear to inhibit the progress of osteolysis. As far as treatment, revision surgery is able to reconstruct the joint by replacing partial or total prosthesis and repair the defect by bone grafting according to intraoperative assessment.

Journal Article↗
PubMed2001

Necrotising fasciitis of a limb.

Between January 1992 and December 1998, we treated 24 patients with necrotising fasciitis of a limb. There were 15 men and nine women with a mean age of 59.8 years (5 to 86). The infection was usually confused with cellulitis. Exquisite pain and early systemic toxicity were the most consistent clinical features. Diabetes mellitus and hepatic cirrhosis were the most commonly associated medical diseases. One third of the patients died. Those with involvement of the limbs above the knee or elbow on admission had a significantly higher rate of mortality than those with distal lesions (Fisher's exact test, p = 0.027). There was no correlation between mortality and advanced age (Student's t-test, p = 0.22) or between amputation and survival (Fisher's exact test, p = 0.39).

Adolescent↗
PubMed2000

A study of surgical approaches to retinal vascular occlusions.

OBJECTIVE: To develop a surgical approach to retinal vascular occlusive diseases. METHODS: Surgical manipulations were performed on the retinal vasculature to explore the feasibility of retinal vascular surgery. In a human cadaver eye model (25 procedures, 21 eyes), we performed (1) cannulations of retinal blood vessels with a flexible stylet and (2) arteriovenous sheathotomies. Histological findings were correlated with surgical outcomes. In an in vivo model (6 eyes, 5 animals), we examined the technical feasibility and anatomical outcome of surgical penetration of retinal blood vessels. RESULTS: Cannulations of branch retinal arterioles were successful in 7 of 9 procedures, cannulations of branch retinal venules were successful in 1 of 3 procedures, cannulations of central retinal arteries were successful in 0 of 2 procedures, and cannulations of central retinal veins were successful in 2 of 4 procedures. Arteriovenous sheathotomies were successful in 4 of 7 procedures. In the in vivo model, surgical penetration of retinal blood vessels was accomplished in 5 of 6 eyes. Immediately postoperatively, thrombus formation with obstruction of the retinal vasculature was observed. At 2 weeks postoperatively, the retinal vasculature was completely patent. CONCLUSIONS: Multiple surgical techniques aimed at assisting recanalization of occluded retinal vasculature have been evaluated. Retinal vascular surgery has become more feasible and deserves further investigation.

Aged↗
PubMed2000

Silent compartment syndrome complicating total knee arthroplasty: continuous epidural anesthesia masked the pain.

Posterior dislocation is an uncommon complication of total knee arthroplasty (TKA) using a posterior stabilized total knee prosthesis, and it usually results from flexion instability. Acute posterior dislocation of a posterior stabilized prosthesis complicated by compartment syndrome of the leg has not previously been reported in the literature. We report a 62-year-old woman with posterior dislocation of her posterior stabilized TKA when her knee was in extension. It was further complicated by compartment syndrome with severe muscle necrosis. The diagnosis of compartment syndrome was delayed, partly because of continuous epidural anesthesia that completely abolished the pain and partly because of the low index of suspicion, as compartment syndrome is not well recognized as a possible complication of TKA. This case report strongly emphasizes that continuous epidural anesthesia is contraindicated in the case of complicated TKA because important clinical cues to neurovascular complications could be masked.

Anesthesia, Epidural↗
PubMed2000

Primary total hip arthroplasty in patients with ankylosing spondylitis.

The results of total hip arthroplasty in a group of patients with ankylosing spondylitis are described. Ninety-five arthroplasties were performed in 56 men and 2 women whose average age at operation was 38.9 years (standard deviation [SD], 11.6; range, 19.2-78.8). They were followed for an average of 135.4 months (SD, 81.6; range, 24.4-331.2). We encountered 4 deep infections necessitating the removal of prostheses. Two of 3 dislocations were anterior dislocations. Nineteen arthroplasties were revised at an average of 162.0 months (SD, 49.6; range, 55.1-250.5) after the primary surgery; 9 of them had only the acetabular component revised because of aseptic loosening. Hyperextension of the hips is a common phenomenon that can lead to surgical error and predispose the prosthesis to anterior dislocation.

Adult↗
PubMed2000

Axial alignment of the lower extremity in Chinese adults.

BACKGROUND: The restoration of normal axial alignment of the lower extremity is important to surgeons who perform reconstructive surgery of the knee. However, data on the normal alignment of the lower extremity in Chinese adults are not available. METHODS: The axial alignment of the lower extremity in twenty-five adult male and twenty-five adult female volunteers of southern Chinese origin was measured on weight-bearing radiographs of the entire lower limb. The mean age was twenty-four years for the male volunteers and twenty-three years for the female volunteers. The results were compared with those of two similar studies of white volunteers in the United States. RESULTS: The medial inclination of the tibial plateau in the Chinese subjects (mean and standard deviation, 5.4 +/- 2.5 degrees for women and 4.9 +/- 2.3 degrees for men) was greater than the commonly reported 3 degrees. The extremities of the Chinese women were found to have a mean of 2.2 +/- 2.5 degrees of varus alignment, and those of the Chinese men had a mean of 2.2 +/- 2.7 degrees of varus alignment. CONCLUSIONS: Compared with the white subjects described in the studies by Moreland et al. and Hsu et al., the Chinese subjects had significantly larger medial inclination of the knee joint (knee-joint obliquity) (p < 0.005) and the female Chinese subjects had significantly more varus alignment of the lower extremity (p < 0.025). CLINICAL RELEVANCE: Five degrees of external rotation of the femoral component, instead of the commonly reported 3 degrees, may be required to obtain a rectangular flexion gap in total knee arthroplasty in Chinese patients. The racial difference in the knee-joint obliquity may contribute to the racial difference in the ratio of knee osteoarthritis to hip osteoarthritis. Additional studies are necessary to confirm this relationship.

Adult↗